Radiological sources are deployed in irradiation facilities for such purposes as sterilization of health care products including pharmaceuticals, deterrence of spoilage of food and agriculture products, and modification of materials such as polymers. Gamma ray emitters such as cobalt-60 and cesium-137 are popular radiological sources for such applications. The use of cesium-137 is typically limited primarily to small (desk-size) self-contained, dry-storage irradiators that are used for such applications as irradiation of blood and for insect sterilization. Cobalt-60 is typically used in large (room-size) devices for irradiating large volumes of produce and equipment. The level of radioactivity from such cobalt-60 sources is astounding, generally in a range from tens of kCi (kilo-curies) to several MCi (mega-curies). These radiological sources may be targets for malevolent actions by vandals intent upon damaging or destroying such devices, or by terrorists intent upon stealing a radiological source to make a “dirty bomb” that would create mayhem by dispersing radioactive materials in a public area. What are needed therefore are systems for protecting radiological sources from such tampering or theft.